Inorganic chemistry and the periodic table Flashcards
What happens to the atomic radius going down group 2?
The atomic radius increases down the group due to the addition of additional shells
What happens to the reactivity going down group 2?
The reactivity increases. This is because there is increased electron shielding and increased atomic radius down the group. This makes the 2 outer electrons easier to lose as they have a weaker attraction to the nucleus.
What happens to the ionisation energy going down the group?
The first ionisation energy decreases down the group due to a greater atomic radius and increased shielding. This makes it easier for the electron to be removed.
What do group 2 metals react with water to produce?
They react with water to produce a metal hydroxide and hydrogen. The metal hydroxide forms as an alkaline solution and is why the group 2 metals are known as the alkaline earth metals.
Mg + 2H20 ->
Mg(OH)2 + H2
How does magnesium react with liquid water?
very slowly
How can the reaction between magnesium and liquid water be sped up?
with steam, as this provides the reaction with extra energy.
What happens when magnesium burns in steam?
a bright white flame is produced and hydrogen and magnesium oxide are produced.
(Mg + H20 -> Mg0 + H2)
what happens when group 2 metals react with chlorine?
metal chlorides are produced. These are all white precipitates.
Mg + Cl2 ->
MgCl2
What happens when group 2 meals react with oxygen?
metal oxides are produced
What can strontium and barium react with excess oxygen and heat to form?
Metal peroxides
What is the general equation of the reaction between group 2 metals and oxygen?
2M + 02 -> 2MO
What is the equation for the reaction between strontium/barium and oxygen?
M + 02 -> M02
What do group 2 metals react with dilute acids to produce?
bubbles of hydrogen gas and solutions of metal compounds.
X + 2HCl->
XCl2 + H2
X + H2S04->
XSO4 + H2
X + 2HNO3 ->
H2 + X(N03)2
What is HCl?
hydrochloric acid
What is H2SO4?
Sulfuric acid
what is HNO3?
nitric acid
What do group 2 hydroxides react with dilute acid to produce?
salt and water. This is a neutralisation reaction
What is the salt formed in neutralisation reactions dependant on?
The acid used
what salt does hydrochloric acid form?
chloride salts
what salt does sulfuric acid form?
sulfate salts
what salt does nitric acid form?
nitrate salts
Calcium hydroxide + Hydrochloric acid ->
calcium chloride + water
what happens to the solubility of group 2 hydroxides going down group 2?
the solubility of the group 2 hydroxides increases going down the group
what happens to the solubility of sulfates going down group 2?
the solubility of sulfates decreases down group 2, meaning that magnesium sulfate is the most soluble and barium sulfate is the least soluble
what can barium chloride be used to test for?
sulfate ions, as it reacts to form barium sulfate which forms as a white precipitate when sulfate ions are present.
Ba2+ + S042- ->
BaS04
do group 2 carbonates and nitrates undergo thermal decomposition to produce solid metal oxides and a variety of gases?
yes
what do group 2 carbonates produce when they undergo thermal decomposition?
a metal oxide and carbon dioxide
as you go down group 2, is it true that more heat is needed for thermal decomposition ?
yes, because the ions increase in size and the carbonates and nitrates increase in thermal stability
what do the group 2 nitrates produce when they undergo thermal decomposition?
metal oxide, nitrogen dioxide, oxygen
how can group 1 and group 2 metals be identified?
using a flame test
describe the steps for the flame test
1) Take a nichrome wire and clean it by placing it into a solution of concentrated hydrochloric acid and then into a blue bunsen burner flame
2) Repeat this cleaning until there is no colour produced in the flame
3) Dip the wire into the unknown metal compound and place it into the flame. Observe the
flame colour produced
what colour does lithium show in the flame test?
red
what colour does sodium show in the flame test?
orange/yellow
what colour does potassium show in the flame test?
lilac
what colour does magnesium show in the flame test?
no colour
what colour does calcium show in the flame test?
brick red
what colour does strontium show in the flame test?
crimson red
what colour does barium show in the flame test?
pale green
how can the formation of the colours in the flame test be explained?
by electron transitions
describe the flame test and electron transitions
Electrons exist in orbitals and when energy (such as that supplied by a bunsen burner flame) is absorbed by the species, some electrons will be promoted to orbitals which have a higher energy. The electrons will then drop back down to the original orbital they were in and during this process they release energy, some of which is in the form of light..
The colour produced depends on the wavelength of the light energy emitted. When some electrons drop back down to their original orbital, the energy emitted may not have a wavelength in the visible light part of the electromagnetic spectrum, which explains why not all atoms and ions produce a colour in the flame test.
what do group 7 elements need to do in order to gain a full outer shell?
they need to gain 1 electron to form a 1- ion
why does the atomic radius increase going down group 7?
due to the addition of more elctron shells
what happens to the electronegativity going down group 7?
Electronegativity decreases because the atomic radius and shielding increases. So, electrons in the outer shell are less strongly attracted to the nucleus and so are more easily removed
what type of molecules are group 7 elements?
Simple covalent molecules that are held together by London forces
What happens to the melting/boiling point going down group 7?
The melting/boiling points increase. This is because the strength of the London forces increases with the increase in relative atomic mass . This means that more energy is required in order to overcome them
What happens to the reactivity going down group 7?
The reactivity decreases. This is because as the atomic radius increases, it becomes to gain an electron because the attraction between the nucleus and the electron is weakened due to shielding.
Why do the halogens act as good oxidising agents?
Because they accept electrons from the species being oxidised and reduced.
Why does the oxidising power of the halogens decrease as you go down the group?
Because their ability to attract electrons decreases due to shielding and a greater atomic radius
What do the relative oxidising strengths mean a halogen will do?
the relative oxidising strengths mean a halogen will displace any halide beneath it in the periodic table. Hence, Cl2 will displace Br- and I- ions, and I2 will not displace any halide ions
What are halide ions?
The negative ions of halogens
Why are halide ions good reducing agents?
Because they are oxidised and they donate electrons to the species being reduced
What happens to the reducing power of halide ions going down group 7?
Going down group 7, the reducing power of halide ions increases
Why does the reducing power of halide ions reduce going down group 7?
Because electrons are easier to lose from larger ions due to shielding and a larger atomic radius
What do the redox reactions between group 7 halides and H2SO4 (sulfuric acid) vary depending on?
They vary depending on the reducing ability of the halide ion
How can the reducing ability of the halide ion be observed?
By the relative reactions of the halides with sulfuric acid
NaF + H2SO4 ->
NaHSO4 + HF
NaCl + H2SO4 ->
NaHSO4 + HCl
Sodium Fluoride + Sulfuric acid ->
Sodium Sulfate + Hydrogen fluoride
Sodium Chloride + Sulfuric Acid ->
Sodium Sulfate + Hydrogen Chloride
Will HF and HCl just be observed as misty fumes?
Yes
NaBr + H2SO4 ->
NaHSO4 + HBr (misty fumes)
2HBr + H2SO4 ->
Br2 + SO2 + 2H20 (orange fumes)
The greater the reducing power…..
the further the reaction will proceed as the halide is powerful enough to reduce more species
What happenes to the reducing power going down group 7?
The reducing power increases
What happens in a disproportionation reaction?
A substance is both oxidised and reduced
What does chlorine react with cold water to produce?
to produce chlorate(I) ions (ClO - ) and chloride ions via a disproportionation reaction. The oxidation state goes from zero to both +1 and -1
(Cl2 + H20 -≥ Cl0- + Cl- + 2H+)
(Cl2 + H20 -≥ Cl0- + Cl- + 2H+)
Where is this reaction used?
In water treatment systems where chlorine is used in small quantities to kill bacteria. This poses some risks as chlorine can be toxic ; however the benefits of clean, treated water outweigh the risks
Write the equation for the disproportionation reaction between chlorine and cold, dilute sodium hydroxide
2NaOH + Cl2 -≥ NaCl0 + NaCl+ H20
Write the equation for the disproportionation reaction between chlorine and hot, dilute sodium hydroxide
6NaOH + 3Cl2 -≥ 5nacl + NaClO3 + 3H20
Do Group 1 and Group 2 metals react with chlorine gas to form metal chlorides?
Yes
What colour precipitates do metal chlorides form?
White
When group 2 metals react with chlorine gas is chlorine reduced or oxidised?
Chlorine is reduced
When group 2 metals react with chlorine gas is the metal reduced or oxidised?
The metal is oxidised
Mg + Cl2 -≥ MgCl2
What does Magnesium’s oxidation number change to?
From 0 to +2
Mg + Cl2 -≥ MgCl2
What does Chlorine’s oxidation number change to?
From 0 to -1
What happens when halide ions are combined with acidified silver nitrate?
They form different coloured precipitates. This helps to identify which halide ion is present in a solution
What happens when chlorine reacts with acidified silver nitrate (AgNO3)?
A white precipitate is formed (AgCl)
What happens when bromine reacts with acidified silver nitrate (AgNO3)?
A cream precipitate is formed (AgBr)
What happens when iodine reacts with acidified silver nitrate (AgNO3)?
A yellow precipitate is formed (AgI)
What happens when chlorine reacts with dilute ammonia?
The precipitate dissolves
What happens when bromine reacts with dilute ammonia?
There’s no change - precipitate remains cream
What happens when iodine reacts with dilute ammonia?
There’s no change - the precipitate remains yellow
What happens when chlorine reacts with concentrated ammonia?
The white precipitate dissolves
What happens when bromine reacts with concentrated ammonia?
The precipitate dissolves
What happens when chlorine reacts with concentrated ammonia?
There’s no change, the precipitate remains white
What do hydrogen halides react with ammonia gas to form?
Ammonium salts
HCl + NH3 -≥
NH4Cl
HBr + NH3 -≥
NH4Br
HI + NH3 -≥
NH4I
What do hydrogen halides react with water to form?
Dilute acids. In solution, these strong acids dissociate to release their halide ions and hydrogen ions. The hydrogen ions form a hydroxonium ion with water molecules in solution. The resulting solution is acidic .
HCl + H2O -≥
Cl- + H3O+
HBr + h20 -≥
Br- + H30+
HI + H20 -≥
I- + H30+
What are sulfate ion (So42-) tested for using?
acidified BaCl 2
barium sulfate
which reacts to form a white precipitate of barium sulfate
BaCl2 + XSO4 -≥
BaSO4 + XCl2
Carbonate (CO 3 2- ) and Hydrogencarbonate (HCO 3 - )
When an acid such as HCl is added, the substance containing the carbonate ions will fizz and CO 2
gas is given off . This gas can be collected and bubbled through limewater which will turn
cloudy , confirming its identity as carbon dioxide.
XC03 +2HCl -≥ CO2 + H20 + XCl2
Ammonium (NH 4
+ )
If ammonium ions are present, adding NaOH and gently warming results in the formation of ammonia gas , which is basic . Therefore, the presence of ammonium ions can be tested by holding damp red litmus paper over a petri dish of the substance being tested. It will turn blue if ammonium ions are present.
🖐️
Hih
Hihi
